In general, an electric automobile has a wheel driving motor. This type of an electric automobile has lately attracted considerable attention, because such an electric automobile is said to solve greenhouse effect problems and air pollution problems caused by exhaust gases containing carbon dioxide from current internal combustion engine type automobiles.
However, both the power and the torque of an electric automobile are considerably less than those of the internal combustion engine type automobile. Furthermore the distance range of the electric automobile per one charge cannot be said to be sufficient because of the low efficiency of the wheel driving motor and the small capacity of the battery of the electric automobile.
As the power output of the wheel driving motor increases, the quantity of heat generated by the wheel driving motor also is increased, so that coils of the wheel driving motor may burn because of an abnormal temperature rise of the motor and the motor efficiency of the wheel driving motor may decrease because of magnetization reduction of the magnet. Accordingly, the efficient cooling of the wheel driving motor in order to maintain the efficiency of an electric automobile has been a great problem.
A new cooling apparatus for cooling the wheel driving motors of an electric automobile has been developed. This cooling apparatus uses cool air generated by an air conditioner of the automobile. Such an air conditioner uses a refrigerant.
The cooling apparatus has an air pipe, a damper and a fan, which convey one part of the cool air for cooling the interior of the automobile to the front and rear wheel driving motors.
In this cooling apparatus, the sufficiently cool air may be conveyed to the front wheel driving motor, because the air conditioner is generally provided at the side of the front wheel of the automobile. However, the cool air conveyed to the rear wheel driving motor may be heated before reaching the rear wheel driving motor, because of the length of the air pipe to the rear wheel driving motor. Therefore, the rear wheel driving motor cannot be sufficiently cooled.
Both the front and rear wheel driving motors also cannot be sufficiently cooled when the cool air cools only the surfaces of the front and rear wheel driving motors. Furthermore, the cooling apparatus is in need of a large fan having a large volumetric delivery in order to convey the cool air to the rear wheel driving motor, which causes problems in that a large power consumption is required.